Hybrid variable external gear pump

ABSTRACT

A pump comprising a housing having a first cavity and a second cavity, where the first cavity has a first motor and a pump element located therein. The first cavity is also connected to an external gear connected to the outside of the housing for receiving rotation power from a vehicle engine. The second cavity has a second motor that selectively connects to the pump element in the first cavity to provide toque.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/692,070, filed Aug. 22, 2012.

FIELD OF THE INVENTION

The present disclosure relates generally to an improved pump, and moreparticularly, to an improved hybrid variable external gear pump for usein a transmission for a vehicle such as an automobile, truck, van,utility, industrial equipment, fleet, cargo or the like.

BACKGROUND OF THE INVENTION

Many transmissions, engines, transfer cases and other power transferringdevices are equipped with oil pumps for lubrication or other pressurizedfluid supply. Internal oil pumps are typically continuously driven.While known arrangements are fairly simple to construct, continuously,mechanically driving the pump may not be the most efficient way ofoperating the vehicle, let alone even possible in some electric vehicleapplications. During certain modes of vehicle operation, the input shaftdriving the pump may rotate at relatively high speed thereby producingrelatively high fluid flow at a time when relatively low or no fluidflow is required. The energy to drive the pump during these modes ofoperation is not providing value and may be considered inefficientwaste.

It is generally known to have a variable displacement vane pump for usein a transmission in a vehicle. One particular example is disclosed inU.S. Pat. No. 4,342,545, to Schuster, the entire contents of which areincorporated herein by reference thereto. Variable displacement pumpsare generally known in transmission control systems, however, theseprior art devices have generally been of the gerotor or sliding ringtype in which the control thereof is maintained by a spring. It is alsogenerally known in electric vehicle applications to provide two pumps—amechanical pump driven by a power take off from the engine and anelectric motor-driven pump for use when the engine is not running. Thisadds significant expense and complexity as well additional potentialfailure modes and control issues. There is also known an externallymounted electric fluid pump for pumping fluid within a powertransmission device as disclosed in US Patent Application PublicationNumber 2010/0290934A1, the entire contents of which are incorporatedherein by reference thereto.

Despite the long known solutions, there remains a significant need toprovide an improved variable displacement vane pump capable of providingimproved performance and gains in efficiency and packaging of the pump.In spite of the long known solutions, there remains a significant needto provide an improved variable displacement pump that can overcome theproblems of the known art.

SUMMARY OF THE INVENTION

A pump comprising a housing having a first cavity and a second cavity. Aprimary shaft extending through the first cavity having a first end anda second end with a first motor in the cavity coupled to a second end ofthe primary shaft. A drive gear coupled to the first end of the primaryshaft by a one way clutch coupling the drive gear and the primary shaftsuch that the drive gear can rotate the primary shaft in a firstdirection. The first motor is coupled to the second end of the driveshaft and can rotate the drive shaft in an opposite direction. The oneway clutch prevents such rotation from being transferred to the drivegear.

A second shaft extends through the second cavity and is connected to asecond motor located in the second cavity. The second shaft has a firstend rotatably supported in the housing and a second end coupled to thesecond motor. The second cavity also has a first failsafe spring locatedproximal to the first end of the second shaft and a second failsafespring located proximal to the second end of the step motor shaft. Afirst seal and a second seal with a second shaft positioned gear betweenthe seals, are coupled to the step motor shaft for contacting andproviding torque to a pump element in the first cavity.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a perspective view of an exemplary embodiment of an outerrotor drive and pump according to the present disclosure;

FIG. 2 is an alternate perspective view of the outer rotor drive andpump of FIG. 1;

FIG. 3 is a further alternate perspective view of the outer rotor driveof FIG. 1;

FIG. 4 is a partial, perspective view of the exemplary embodiment of theouter rotor drive and pump of FIG. 1 according to the presentdisclosure;

FIG. 5 is an exploded perspective view of the exemplary embodiment ofthe outer rotor drive and pump of FIG. 1 according to the presentdisclosure;

FIG. 6 is an alternate exploded perspective view of the exemplaryembodiment of the oil pump of FIG. 1 according to the presentdisclosure;

FIG. 7 is a perspective view of the second shaft gear of the secondmotor of pump of FIG. 6 according to the present disclosure; and

FIG. 8 is an exploded perspective view of the second gear of the secondmotor of pump of FIG. 7 according to the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

Referring in general to all of the Figures, the present disclosure andteachings described herein provide for an oil pump 10 and oil pumpoperating system for use with a cooling system in a transmission orengine. The oil pump 10 is design so it can be driven using multiplesources. The oil pump 10 includes a housing 11 having a pump portion 12and a motor portion 14 that is coupled to the pump portion 12 at one end16 of the pump portion 12. The interiors of the pump and motor portionshave a first cavity 18 and second cavity 19, which are both generallycylindrically shaped and aligned side-by-side as shown in the Figures.The first cavity 18 is connected to an inlet 13 and outlet 15 disposedthrough the housing 11. Fluid such as oil or transmission fluid entersthe housing 11 through the inlet 13 and exits an outlet 15. The movementof fluid through the housing 11 is caused by a pump element 31positioned in the first cavity 18. The pump element 31 in the presentembodiment of the invention is a gerotor formed on the primary shaft 30.

The motor portion 14 is closed at an opposite end using a housing cover20. The motor portion 14 includes a first motor 22 in the first cavity18 and a second motor 24, (a generally smaller, step motor), located inthe second cavity 19. The first motor 22 and second motor 24 are coupledto a controller 26 located between the first motor 22 and second motor24 and the end of the motor portion and the housing cover 20.

In one exemplary embodiment as shown in the Figures, the oil pump 10 ofthe present disclosure preferably includes only a single controller 26for controlling both the first motor 22 and second motor 24, thecontroller 26 being located at an end of the motor portion 14. In theexemplary embodiment shown in the Figures, locating the controller 26 atthe one end of the motor portion 14 of the oil pump 10 and co-locatingthe motors as disclosed allows for one controller to manage the twomotors to thereby provide a lower cost controller and lower cost oilpump. In one alternate embodiment, it is contemplated that twocontrollers are used wherein each controller controls a single motor. Ina further alternative embodiment, it is contemplated that twocontrollers are used wherein each controller controls a single motor andincludes a backup controller for the other motor to provide redundancy.

In one exemplary aspect, the oil pump 10 is driven using power take offfrom the engine using an external gear 28 coupled to the power take off.The external gear 28 is coupled to the power take off from one of theengine or the transmission and is driven thereby to cause rotation ofthe oil pump 10. The external gear 28 is coupled to a primary shaft 30located in the first cavity 18 in pump portion 12 of the pump 10 using afastener 32, such as the screw shown in the Figures, or other known andappropriate coupling device.

The external gear 28 of the pump 10 includes a one way clutch 34. Theone way clutch 34 is configured so that rotation of the external gear 28in one direction will be transferred directly to the primary shaft 30,and causes it to rotate directly with the external gear 28. The pumpelement 31 is connected to the primary shaft 30 and rotates in responseto torque inputted from the external gear 28 or torque inputted from thefirst motor 22 or the second motor 24. Rotation of the external gear 28in the opposite direction does not cause rotation of the primary shaft30. More significantly, rotation of the primary shaft 30 does not causerotation of the external gear 28 because the one way clutch mechanism isdesigned to only allow forces to be transferred from the external gear28 to the primary shaft 30 and not from the primary shaft 30 to theexternal gear 28.

Accordingly, in one mode of operation of the oil pump 10, such as whenthe engine is operating in a start/stop mode, (also known as a start andgo mode or application), the engine is stopped when the vehicle isstopped and there is no demand from the operator for the vehicle engineto run. When the engine is stopped, the engine and transmission do notrotate and there is no operating power take off from the engine ortransmission that can cause the external gear 28 to rotate. Thereforethe oil pump 10 cannot be driven by the external gear 28. In this mode,the oil pump 10 is operated by the first motor 22, which is a brushlessdirect current (“BLDC”) motor using power, such as electricity, to causethe first motor 22 to rotate and thereby rotate the primary shaft 30 andpump element 31. In this mode, the one way clutch prevents rotation ofthe shaft from being transferred to the external gear 28 and back intothe power take off mechanism and/or the engine and transmission. TheBLDC motor can be of any known or appropriate type and preferably has apower rating of between about 50W and 80W, sufficient to drive the pump10 in the start and go mode or application.

As shown in the Figures, the second motor 24, of the oil pump 10 and itscontrol, is a step motor located in the end near the first motor 22 andin the second cavity 19 of the motor portion 14 aligned with the pumpportion. The second motor 24 is coupled to a second shaft 36. The secondshaft 36 includes a bearing 38 for supporting rotation of the secondshaft 36 within the second cavity 19. The second shaft 36 has a secondshaft gear 37 that engages with the pump element 31 in order to applytorque from the second motor 24 to the pump element 31 through thesecond shaft gear 37. The second shaft gear 37 has seals 39, 39′ oneither side that prevent fluid from leaking from the first cavity 18 tothe second cavity 19. The seals 39, 39′ are optional and it is withinthe scope of the invention for some embodiments to allow fluid to flowinto the second cavity 19. The second motor 24 is preferably a threephase stepper motor (having an operating range of approximately 3W-4Wthat operates to change the displacement of the pump and to the forcebalance of the second shaft 36 with bearing 38. The use of the secondmotor 24 changes the displacement of the pump and thereby reduces thetorque for operating the pump at the cold start. In one embodiment, thesecond motor 24 preferably includes an over molded motor winding with anintegrated bus bar and also includes smart control implemented in thecontroller 26 to keep high accuracy of control and high dynamicregulation function.

In one exemplary embodiment as shown in the Figures, the oil pump 10further include an oil flow for cooling portions of the controller 26,or MOSFETS of the step motor and/or the BLDC motor. In one alternateexemplary embodiment, it is contemplated that the arrangement of thecontroller 26 and the motors 22, 24 of the oil pump 10 of the presentdisclosure further includes a robust, low-cost Bx_By flux positionsensor integrated in PCB of the controller 26. With the arrangement ofthe oil pump 10 and motors 22, 24 of the present disclosure, the firstmotor 22 and controller 26 may be used to generate regeneration energyduring operation of the oil pump 10 when the engine reduces speed, suchas when the vehicle is slowing down and there is a lower demand for oilpumping within the transmission and engine and the transmissioncontinues to rotate and drive the external gear 28 of the oil pump 10and the motors 22, 24 can be used to generate electricity that can bestored for later use. In one exemplary embodiment, upon operation of thesecond motor 24, failsafe spring(s) 40, 40′ move the second shaft gear37 coupled to the second shaft 36 to a full displacement position ifthere is issue in the electrical controller 26. The conversion ofrotational movement of the second motor 24 to linear movement of thesecond shaft gear 37 is accomplished using a lead screw 42 or matedthreads formed between a gear support 41 and the surface of the secondshaft 36. FIG. 8 shows how the second shaft gear 37 is press fit ontothe gear support, that is connected to one of the seals 39′. The gearsupport 41 is used to connect the seals 39, 39′ and second shaft gear 37onto the second shaft 36.

The oil pump, its motors and the controller can be operated using anyknown or appropriate communications protocol including, but not limitedto, CAN or LIN communication protocols.

The description of the invention is merely exemplary in nature and,thus, variations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

What is claimed is:
 1. An electric gear oil pump comprising: a housing having a first cavity and a second cavity and an inlet and an outlet; a drive gear connected to the housing; a first motor in the first cavity; a primary shaft extending through the first cavity, said primary shaft being connected to both the drive gear and the first motor, wherein the first motor and the drive gear supply torque to the primary shaft; a pump element connected to and rotatable with the primary shaft for pumping fluid through the inlet and the outlet of the housing; a second shaft extending through the second cavity, the second shaft has second shaft gear configured to selectively engage the pump element in order to input torque to the primary shaft and pump element when the drive gear is not supplying torque to the primary shaft; and a second motor contained in the second cavity and selectively drives the second shaft.
 2. The electric gear oil pump of claim 1 further comprising: a clutch member connected between the drive gear and the primary shaft, wherein the drive gear selectively supplies torque to the primary shaft from an engine in one direction when the clutch member is engaged and the drive gear is disconnected from the primary shaft when the clutch member is disengaged.
 3. The electric gear oil pump of claim 2 further comprising a lead screw connected between the second shaft and the second shaft gear, wherein the lead screw causes the second shaft gear to slide in a linear direction in the second cavity when the second motor is energized, thereby engaging the second shaft gear with the pump element.
 4. The electric gear oil pump of claim 1 further comprising a lead screw connected between the second shaft and the second shaft gear, where in the lead screw causes the second shaft gear to slide in a linear direction in the second cavity when the second motor is energized, thereby engaging the second shaft gear with the pump element.
 5. The electric gear oil pump of claim 1 further comprising single controller contained in the housing, wherein the single controller is configured to control the operation of the first and second pumps.
 6. The electric gear oil pump of claim 1 further comprising: a first failsafe spring located proximal the first end of the second shaft; a second failsafe spring located proximal the second end of the second shaft, wherein the first failsafe spring and second failsafe spring move the second shaft gear to a full displacement position if there is failure of the first motor and the second motor.
 7. The electric gear oil pump of claim 1 further comprising: a first seal coupled to the second shaft; a second seal coupled to the second shaft, wherein the second shaft gear is located between the first seal and the second seal and the first seal and second seal allow the second shaft gear to contact the pump member and prevent fluid from entering the second cavity from the first cavity.
 8. An electric gear oil pump comprising: a housing having a first cavity and a second cavity and an inlet and an outlet; a drive gear connected to the housing; a first motor in the first cavity; a primary shaft extending through the first cavity with one end connected to the drive gear and a second end connected to the first motor, wherein the first motor supplies torque to the primary shaft; a clutch member connected between the drive gear and the primary shaft, wherein the drive gear selectively supplies torque to the primary shaft from an engine in one direction when the clutch member is engaged and the drive gear is disconnected from the primary shaft when the clutch member is disengaged; a pump element rotatable with the primary shaft for pumping fluid through the inlet and the outlet of the housing; a second shaft extending through the second cavity, the second shaft has a second shaft gear configured to selectively engage the pump element in order to input torque to the primary shaft and pump element when the drive gear is not supplying torque to the primary shaft; and a second motor contained in the second cavity and selectively drives the second shaft.
 9. The electric gear oil pump of claim 8 further comprising a lead screw connected between the second shaft and the second shaft gear, wherein the lead screw causes the second shaft gear to slide in a linear direction in the second cavity when the second motor is energized, thereby engaging the second shaft gear with the pump element.
 10. The electric gear oil pump of claim 8 further comprising single controller contained in the housing, wherein the single controller is configured to control the operation of the first and second pumps.
 11. The electric gear oil pump of claim 8 further comprising: a first failsafe spring located proximal the first end of the second shaft; a second failsafe spring located proximal the second end of the second shaft, wherein the first failsafe spring and second failsafe spring move the second shaft gear to a full displacement position if there is failure of the first motor and the second motor.
 12. The electric gear oil pump of claim 8 further comprising: a first seal coupled to the second shaft; a second seal coupled to the second shaft, wherein the second shaft gear is located between the first seal and the second seal and the first seal and second seal allow the second shaft gear to contact the pump member and prevent fluid from entering the second cavity from the first cavity.
 13. An electric gear oil pump comprising: a housing having a first cavity and a second cavity and an inlet and an outlet; a first BLDC motor located in the first cavity; a primary shaft having a first end and a second end; an external gear coupled to the first end of the primary shaft; a one way clutch coupling the external gear and the primary shaft such that the external gear can rotate the primary shaft in a first direction and wherein the BLDC motor is coupled to the second end of the primary shaft and selectively rotates the primary shaft in an opposite direction and the one way clutch prevents such rotation from being transferred to the external gear; a second step motor located in the second cavity; a second shaft having a first end rotatably supported in the housing and a second end coupled to the step motor; a first failsafe spring located proximal the first end of the second shaft; a first seal coupled to the second shaft; a second seal coupled to the second shaft; a second shaft gear coupled to the second shaft and located between the first seal and the second seal; a second failsafe spring located proximal the second end of the step motor shaft; a controller coupled to the BLDC motor and to the step motor; and a cover coupled to the motor portion.
 14. The electric gear oil pump of claim 13 further comprising a lead screw connected between the second shaft and the second shaft gear, wherein the lead screw causes the second shaft gear to slide in a linear direction in the second cavity when the second motor is energized, thereby engaging the second shaft gear with the pump element.
 15. The electric gear oil pump of claim 13 further comprising single controller contained in the housing, wherein the single controller is configured to control the operation of the first and second pumps.
 16. The electric gear oil pump of claim 13 further comprising: a first failsafe spring located proximal the first end of the second shaft; a second failsafe spring located proximal the second end of the second shaft, wherein the first failsafe spring and second failsafe spring move the second shaft gear to a full displacement position if there is failure of the first motor and the second motor.
 17. The electric gear oil pump of claim 13 further comprising: a first seal coupled to the second shaft; a second seal coupled to the second shaft, wherein the second shaft gear is located between the first seal and the second seal and the first seal and second seal allow the second shaft gear to contact the pump member and prevent fluid from entering the second cavity from the first cavity. 